用于太阳电池的p—ZnTe／n—CdTe异质结的研究

从光电转换的基本原理出发,分析了禁带宽度 Eg、薄膜以及异质结对材料的选择原则。在异质结理论的基础上,分析了 p-ZnTe/n-CdTe 异质结的结区结构,在两种材料的界面处,导带底形成了不连续的“断口”,价带顶 p 区一侧形成尖峰,n 区一侧形成凹口。当热平衡时,由于导带中电子从 n 区到 p 区所遇到的势垒大于价带中空穴从 p 区到 n 区的势垒,所以,通过势垒的主要是空穴流。讨论了 p-Zn-Te/n-CdTe 异质结的制作方法及工艺问题。最后,给出了测试结果。     

Vacuum-deposited thin-film p-Se/n-CdSe heterojunction diodes

A preliminary feasibility study has been made of vacuum-deposited thin-film diodes based on the p-Se/n-CdSe heterojunction system. These diodes have excellent rectification properties, including: 1) 70-volt reverse breakdown, 2) 10⁵rectification ratio over a range of 25 volts, and 3) 0.5-volt forward offset voltage. The diodes have a "sandwich-cell" structure formed by depositing a CdSe layer onto a Crystallized layer of Se. This work is still in a preliminary stage. However, the results thus far suggest that these diodes may be suitable for use in thin-film integrated circuits for those specialized circuit applications which require only diodes, resistors, and/or capacitors.     

Au/Pt/Ti/Ni ohmic contacts to p-ZnTe

Ohmic contacts of Au/Pd/Ti/Ni to p-ZnTe show a minimum specific contact resistance of 10^-6 Ωcm² for a p-type doping level of 3×10¹⁹ cm^-3 and at an annealing temperature of 300°C. The Ni and Ti layers are very effective in improving the electrical properties of these contact     

Studies on vacuum deposited p-ZnTe/n-CdTe heterojunction diodes

The present paper reports the fabrication and detailed electrical characterization of p-ZnTe/n-CdTe heterojunction diodes prepared by vacuum deposition method. The possible conduction mechanisms of the heterojunction diode were determined by analyzing the I-V characteristics. The C-V characteristics of the heterojunction diodes were studied to determine the barrier height, carrier concentration and thickness of the depletion region in the heterojunction. A theoretical band diagram of the heterojunction was drawn based on Anderson’s model.     

SiGeC异质结功率二极管通态特性研究

研究了一种大功率低功耗p+(SiGeC)-n--n+异质结二极管结构,分析了Ge、C含量对器件正向通态特性的影响。结果表明:与常规的Si p-i-n二极管相比,在正向电流密度不超过1000 A/cm2情况下,p+(SiGeC)-n--n+二极管的正向压降有明显的降低。当电流密度为10 A/cm2时,Si p-i-n二极管的压降为0.655 V,而SiGeC异质结二极管的压降只有0.525 V,大大降低了器件的通态功耗。在相同正向电流密度的条件下,SiGeC异质结二极管在n-区存储的载流子比Si二极管的减少了1个数量级以上,这导致前者的关断时间远小于后者。     

在a-Si:H/a-SiN_x:H超晶格中导电机制的研究(英文)

We have studied the conduction mechanism of a series of a-Si:H/a-SiNx:H multi-layers samples which have an identical sublayer thickness and periodic numbers, except the ratio of N/Si in a-SiNx:H sublayers. It is shown that the temperature characteristic of conductivity of these samples has a kink point in the range of 120-140℃. The kink temperature and the acttivation energy of conductivity are related to the N/Si ratio in the a-SiNx:H sublayers. We recognized preliminarily that the mechanism above and below the kink temperature could be the bulk or the interfacial conduction in a-Si:H well layers.     

The ohmic contact formation mechanism of Au/Pt/Pd ohmic contact to p-ZnTe

The ohmic contact formation mechanism and the role of Pt layer of Au(500Å) Pt(500Å)/Pd(100Å) ohmic contact to p-ZnTe were investigated. The specific contact resistance of Au/Pt/Pd contact depended strongly on the annealing temperature. As the annealing temperature increased, the specific contact resistance decreased and reached a minimum value of 6×10^?6 Θcm² at 200°C. From the Hall measurement, the hole concentration increased with the annealing temperature and reached a maximum value of 2.3×10¹⁹ cm^?3 at 300°C. The Schottky barrier height decreased with the increase of annealing temperature and reached a minimum value of 0.34 eV at 200°C and it was due to the interfacial reaction of Pd and ZnTe. Therefore, the decrease of contact resistance was due to the increase of doping concentration as well as the decrease of Schottky barrier height by the interfacial reaction of Pd ZnTe. The specific contact resistances of Au Pd, Au/Pt/Pd and Au/Mo/Pd as a function of annealing time was investigated to clarify the role of Pt layer.     

Growth and characterization of ZnTe:N; p-ZnTe/n-AISb diodes

In recent months the successful p-doping of ZnSe and Zn(S,Se) using a nitrogen plasma source during growth by molecular beam epitaxy was one factor leading to the realization of diode lasers and light emitting diodes. This paper reports the results of the nitrogen doping of ZnTe using similar techniques. Doping levels exceeding the 10¹⁹ cm⁻³ range are reported along with electrical, optical, and microstructural characterization. The nitrogen-doped ZnTe is used to implement p-ZnTe/n-AISb diodes; the growth and characterization of these hetero-junction diodes are described.     

Formation Mechanism of Fullerene Cation in Bulk Heterojunction Polymer Solar Cells

The charge carrier dynamics in blend films of [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PCBM) and conjugated polymers with different ionization potentials are measured using transient absorption spectroscopy to study the formation mechanism of PCBM radical cation, which was previously discovered for blend films of poly[2‐methoxy‐5‐(3,7‐dimethyloctyloxy)‐1,4‐phenylenevinylene] (MDMO‐PPV) and PCBM. On a nanosecond time scale after photoexcitation, polymer hole polaron and PCBM radical anion are observed but no PCBM radical cation is found in the blends. Subsequently, the fraction of polymer hole polarons decreases and that of PCBM radical cations increases with time. Finally, the fraction of PCBM radical cations becomes constant on a microsecond time scale. The final fraction of PCBM radical cation is dependent on the ionization potential of polymers but independent of the excitation wavelength. These findings show that the formation of PCBM radical cation is due to hole injection from polymer to PCBM domains. Furthermore, the energetic conditions for such hole injection in polymer/PCBM blend films are discussed on the basis of Monte Carlo analysis for hole hopping in a disordered donor/acceptor heterojunction with varying energetic parameters.     

聚合物半导体PAn/Si异质结(英文)

The P type semiconducting polymer polianiline (PAn) films have been prepared on n and p type si chips by photo-electrochemical and electrochemical polymerization, and so the semiconducting polymer PAn/silicon heterojunctions have been fabricated. The I dark-V and I photo-V curves, as well as C-V curves at different frequencies have been measured and the energy band diagrams, the distributions of impurity density and the interface states have been analyzed for the heterojunctions. It is demonstrated experimentally that the n-p Si-PAn heterojunction possesses fine photoelectrical characteristics.     

Fabrication ofn-native oxide/p-ZnTe heterojunctions by the anodic oxidation of ZnTe MBE layers

We demonstrate diode-like behavior betweenp-type ZnTe and its anodic oxide. We describe conditions in which the anodic oxidation process is selective for ZnO formation.N-type conductivity of the anodic oxide is achieved through thermal annealing, giving rise to carrier concentrations of 5 × 10¹⁸ cm^-3. The anodization and the thermal annealing parameters were correlated with Auger Electron Spectroscopy measurements. Structures of anodic oxide/ZnTe have exhibited good rectification properties after brief thermal annealing.     

Variable range hopping conduction in n-CdSe samples at very low temperature

We reanalyzed experimental data already published in Friedman J R, Zhang Y, Dai P, et al. Phys Rev B, 1996, 53(15):9528. Variable range hopping(VRH) conduction in the insulating three-dimensional n-CdSe samples has been studied over the entire temperature range from 0.03 to 1 K. In the absence of a magnetic field, the low temperature conductivity σ of the three samples(A, B and C) obeys the Mott VRH conduction with an appropriate temperature dependence in the prefactor(σ=σ₀ exp[-(T₀/T)^p with p≈0.25). This behavior can be explained by a VRH model where the transport occurs by hopping between localized states in the vicinity of the Fermi level, E_F, without creation of the Coulomb gap(CG). On the contrary, no Efros-Shklovskii VRH is observed, suggesting that the density is constant in the vicinity of the E_F.     

钌基厚膜电阻器传导机理述评

钌基厚膜电阻器传导机理的合理解释为隧道效应。钌基厚膜电阻器电导的温度相关性、电导的电场相关性、电阻的应变效应及其他一些实验现象均可用隧道效应加以解释。文章还介绍了几种传导模型：Ｃａｎａｌｉ的模型给出了与实验现象一致的定性解释；Ｐｉｋｅ的理论计算运用于有效激合能为主要作用的Ｍ２Ｒｕ２Ｏ７型电阻器；Ｗｉｋｌｅｒ证明了电子以弯曲轨道传递的模型是合理的。     

AlGaAs/GaAs Heterojunction bipolar power transistors

An AlGaAs/GaAs heterojunction bipolar transistor with a total emitter periphery of 320 ?m has been developed for power amplifier applications. For the base contact, Zn diffusion was used to convert the n-type emitter material into p-type with a doping of ?1.0 × 1020 cm?3. Because of the highly doped layer, contact resistivity was extremely low (5 × 10?7 ?cm2). At 3 GHz, a CW output power of 320 mW with 7 dB gain and 30% power-added efficiency was obtained. Under pulsed operation, the output power increased to 500 mW with 6 dB gain and 40% power-added efficiency. With further device structure optimisations, the power performance of heterojunction bipolar transistors is expected to rival, or even surpass, that of the GaAs MESFETs.     

InGaAsP／InP异质结光电三极管的制备

介绍了ｎ－ＩｎＰ／ｐ－ＩｎＧａＡｓＰ／０－ＩｎＰ结构的异质结光电三极管制作过程，并获得了对１．３μｍ的入射光，光增益达２２０，用带尾纤的ＧａＡｓ／ＧａＡｌＡｓ发光管测量，光学增益达１４７０。     

GeSi/Si异质结红外摄像器

论述了单片 5 12× 5 12像素的 Ge Si/Si异质结红外摄像器。它的工作原理和 Pt Si/Si肖特基势垒红外摄像器一样。制造 Ge Si/Si异质结采用分子束外延法 ,在 Si片上生长 Ge Si膜。该膜有理想的应力。文章评价了 Ge成份、掺杂浓度、Ge Si膜厚和光谱响应的关系。研究表明器件的最佳工作波长为 8～ 12μm。     

p＋-InP/n-InGaAs/n-InP双异质结结构的微波反射光电导衰减法表征及机理分析

采用微波反射光电导衰减法测量了P -InP/n-InGaAs/n-InP双异质结材料的非平衡载流子寿命分布,通过对非平衡载流子浓度在P n结中衰减过程的分析,建立了在此结构材料中微波反射光电导衰退法测试少子寿命与器件参数之间的联系,并且解释了寿命测试值随温度降低而减小的反常行为.     

SOI／SDB薄膜全耗尽隐埋n—MOSFET导电机理研究

本文详细研究了SOI/SDB薄膜全耗尽隐埋n沟 MOSFET的器件结构及导电机理,建立了明确的物理解析模型,给出了各种状态下器件工作电流的解析表达式。最后,将解析模型的计算结果与实验数据进行了比较和讨论。     

Heterojunction InP/GaInAs phototransistors/bipolar transistorsgrown by MOVPE

Heterojunction InP/GaInAs phototransistors with base terminals have been fabricated by atmospheric pressure metal organic vapour phase epitaxy. When operated as bipolar transistors, the devices exhibit high current gain (>1600) and good junction ideality factors (1.06 for the base/emitter and 1.25 for the base/collector junction). When operated as phototransistors, the devices have large optical gain (>800) at an incident power of 1 μW, at a wavelength of 1.3 μm     

有机/无机复合体异质结太阳电池

利用简单的低温工艺制备了纳米晶纤锌矿结构的ZnO,用高分辨透射电镜(HRTEM)、X射线衍射(XRD)和光致发光(PL)技术进行了表征.利用纳米晶ZnO和共轭聚合物2-甲氧基-5-(3,7.二甲基辛氧基)对苯撑乙烯(MDMO-PPV)制备了结构为ITO/PEDOT:PSS/ZnO:MDMO-PPV/Al的有机/无机复合体异质结太阳电池,作为对比,同时制备了ITO/PEDOT:PSS/MDMO-PPV/Al结构的纯有机聚合物电池.实验结果表明,添加纳米晶ZnO使其能量转换效率提高了约550倍.PL谱测试结果表明这是由于有高电子亲合能的ZnO提高了电子空穴对分离的能力.另外,光伏性能的提高可能也与ZnO引起的电子传输能力的提高有关.此外,本文分析了ZnO:MDMOPPV体异质结电池性能低于传统电池的原因,并提出了进一步提高其性能的方法.